Reinforcing members

ABSTRACT

Parts are provided which combine structural reinforcement of hollow profiles and light weight means of attachment. Optionally, the part may also provide an acoustic baffle. The parts consists of a core coated with expandable structural reinforcing foam on at least part of its surface the core being provided with means for receipt of a nut and means to prevent rotation of the nut. Optionally, a piece of a second expandable material is provided on at least one extremity which can expand to fill the entire cross section of the hollow profile. In a preferred embodiment, the hollow profile is the A, B or C pillar of a vehicle and the nut is used for attaching doors.

CLAIM OF BENEFIT OF FILING DATE

The present application claims the benefit of the filing date of U.K.Application Serial No. 0300159.1 filed Jan. 6, 2003, hereby incorporatedby reference.

FIELD OF INVENTION

The present invention relates to a means for providing structuralreinforcement within hollow frames at positions where parts are attachedto the hollow frames and is particularly concerned with such means whichenable a significant reduction in the weight of the attachment meanswhilst increasing the overall strength of the structure. The inventionis particularly useful with automobiles although it may be used incaravans, aircraft, boats, ships, construction and other similarapplications.

BACKGROUND OF INVENTION

The attachment of a door to a pillar, such as the A pillar of anautomobile provides a good example of the applicability of the presentinvention. The A pillar is typically a hollow metal frame and the dooris attached to the outside of the frame with a nut and a heavy elongatedbolt which extends across the cavity of the hollow frame to prevent theopposed surfaces of the frame collapsing inwards. These elongated boltsare extremely heavy and so, undesirably, add to the weight of thevehicle. They are also expensive.

It is known to provide structural reinforcement in hollow structures bythe provision of a core of reinforcing material coated with foamableadhesive material within the hollow structure. The foamable material isthen activated by heat, typically the temperature in the drying oven ofthe e-coat anti-corrosion coating process so that it foams to fill thespace between the core of reinforcing material and the hollow structure.The foamed adhesive material will also bond the core to the internalsurface of the hollow structure. It has been proposed that suchreinforcing structures may be used around positions of attachment but ithas been necessary to ensure that the reinforcing structure be such thatit allows for passage of the attaching means such as a bolt through thestructure.

SUMMARY OF THE INVENTION

We have now found that providing certain conditions are fulfilled a nutmay be located within a structural reinforcing member allowing secureattachment to be achieved with use of a smaller and lighter bolt. Thestructural reinforcing member including the foam fills the hollowstructure and prevents the opposing faces from collapsing, the functionhitherto performed by the elongated bolt.

Accordingly, the present invention provides a structural reinforcingmember comprising a core coated over part of its surface with anexpandable material wherein the core is provided with means for receiptof a nut and means to prevent rotation of the nut and the location ofthe expandable material on the surface of the reinforcing member is suchthat expansion of the expandable material does not cause foam to cover anut located within the means for receipt of a nut or any bolt attachedto said nut.

In a further embodiment the invention can also provide sound insulationwithin the vehicle structure.

The present invention is particularly useful in the provision ofreinforcement and optionally sound insulation in vehicle A and B pillarsat the positions where the doors are attached to the pillars.Traditionally, doors have been attached to the pillars using extremelylong and heavy nuts and bolts which also act as spacers between the twometal surfaces of the pillar. These make an undesirably highcontribution to the weight of the vehicle. We have now found that, therigid reinforcing member can act as the spacer between the metalsurfaces and may also be provided with means for receiving the nut thatis used for attachment of the door to the pillar. We have found that theexpandable material allows a lighter weight means for securing andproviding spacing which also provides adequate strength andreinforcement. For example, whilst the securing means may continue to bea nut and a bolt the bolt may be an integral part of the structuralreinforcing member and it may be strengthened by the expanded materialand the rigid reinforcing material to enable lighter weight bolts and/ormaterials to be used to produce attachments of comparable strength.Similarly, the securing means may be a nut and the invention enables theuse of a lighter weight nut. The means within the reinforcing memberthat receives the nut is preferably a cavity, which is shaped both toreceive a nut and prevent rotation of the nut. It is also important thatafter foaming the foam does not envelop the nut and/or bolt in orderthat the door can be removed and/or replaced.

In a preferred embodiment, the invention further provides a combinedeffect of structural reinforcement, improved lighter means of attachmenttogether with a baffle providing for instance, sound insulation. Inparticular, the invention provides materials that can be installed inhollow cross-sectional members to provide reinforcement to improve thestructural integrity of vehicles, to enable attachment of parts such asdoors and to provide sound insulation against the noise of air currents.The invention is particularly concerned with the provision of suchmaterials in the pillars of the main body of vehicles particularly atthe bottom of the A pillar close to the lower door attachment where theyprovide the combined reinforcement and insulation effect with a simplerand lighter means of attaching the door to the pillar.

The invention further provides a system whereby these desirableproperties can be provided in an automobile whilst ensuring effectiveprovision of an anti-corrosion coating on the inner surface of thehollow cross-sectional member by the electrocoat process. Theelectrocoat process used in vehicle manufacture is a process in whichthe vehicle structure is passed through a bath of anticorrosion fluidand the vehicle structure is used as an electrode whereby ananticorrosion coating is deposited from the fluid onto the vehiclestructure by electrolysis.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a multisectional profiled member according to an exemplaryembodiment of the present invention.

FIG. 2 is an enlarged view of a portion of the profiled member of FIG.1.

DETAILED DESCRIPTION OF THE INVENTION

The trends in motor vehicle design are towards lighter vehicles toimprove fuel consumption. At the same time, the safety standards andrequirements are becoming more rigorous as indicated by the EuropeanUnion requirements and the Euro-NCAP impact testing. The use of lightermaterials such as aluminum to produce the hollow cross-sectional membersthat are used as vehicle sub frames has lead to the need for additionalreinforcement. There is a need for reinforcement in various locations inthe vehicle structure including the sub frame and upper structure andthe form of reinforcement required can vary from one location in thevehicle to another and from vehicle to vehicle. The present inventiontherefore reduces the weight of vehicle structures and at the same timeimproves the strength of the vehicle structure. In a preferredembodiment those effects are combined with the provision of improvedsound insulation.

There are four main types of application where structural reinforcementis required in vehicles. Crash protection is one type where theprevention of vehicle body deformation is important to provideprotection for the occupants. Energy absorption is another type employedto enhance performance after yield. The reduction of flexing or bodymovement in the vehicle structure particularly to improve durability andreduce stress cracking and the point mobility problems requiring thereduction of resonance by the provision of stiffening are other types.

It is known to provide foamable plastic mouldings within hollow crosssections of vehicles which can be foamed upon application of heat, suchas in the baking step in the electrocoat process. In this way, a foamedbaffle that fills the cross-section to provide sound adsorption can beproduced. Such systems are described in European Patent Applications0383498 and 0611778. The foamed baffle provides sound deadening andvibration resistance. In these systems the entire insert is foamable andit is proposed that the foamable material be chosen so that it will foamduring the baking process which follows the electrocoat processtypically used in vehicle manufacture to provide resistance to metalcorrosion. Such materials may be combined with the structuralreinforcing member of the present invention.

It is also known from WO01/883206 A to provide materials that have acombined reinforcing and sound deadening effect.

In a preferred embodiment, the present invention provides combinedstructural reinforcement and sound deadening for a hollow membercomprising a rigid reinforcing member having a shape that substantiallyconforms to the cross section of the section of the hollow member to bereinforced having a first expandable adhesive material over at least aportion of the surface of said rigid reinforcing member said firstexpandable material forming a structural foam upon expansion which bondsthe reinforcing member to at least part of the internal surface of thestructure, said rigid reinforcing member having on at least oneextremity a second expandable material. The second expandable materialpreferably expands at substantially the same temperature as the firstexpandable material to entirely fill the cross section of the hollowmember beyond the extremity of the rigid reinforcing member to providean acoustic baffle, the rigid reinforcing member being provided withmeans for receipt of a nut and means to prevent rotation of the nut, thefirst and second expandable material being such that when foamed thefoam does not cover a nut located with the means for receipt of a nut orany bolt attached to said nut.

Accordingly, upon expansion of the two expandable materials used in thepreferred embodiment of the invention, a unitary structure is formedwithin the hollow member comprising the rigid reinforcing member bondedat certain positions to the hollow profile member by the structural foamand further comprising a sound insulating foam baffle which entirelyfills the cross section of the hollow profile member at least oneextremity of the rigid reinforcing member, the foam being such that itdoes not impede access to the nut.

The dimensions of the rigid reinforcing member and the thickness andnature of the first expandable material are important to the achievementof the desired structural reinforcement. The exterior shape of thereinforcing member should conform substantially to the cross section ofthe section of the automotive structure it is designed to reinforce. Theshape may vary along the length of the reinforcing member as thedimensions of the cross section of the structure change. The size of thereinforcing member including the first expandable adhesive material andany second expandable material that may be present should be such thatthere is a small clearance between the extremity of the reinforcingmember and the interior walls of the frame of the vehicle to allow forpassage of the electrocoat fluid during the e-coat anti-corrosionprocess. The reinforcing member preferably has a cellular, honeycomb orribbed internal structure to provide reinforcement along severaldifferent axes.

When present, the size of the piece of the second expandable materialthat is provided at the extremity of the rigid reinforcing member shouldalso be such that, in the unfoamed state, there is a clearance betweenthe perimeter of the piece of second expandable material and theinterior walls of the foam of the vehicle to allow for passage of theelectrocoat fluid.

The structural reinforcing member is preferably provided with means forattachment to the interior walls of the frame of the vehicle. The meansof attachment may be clips which fit into receptors in the frame of thevehicle or alternatively they may be receptors formed in the structuralreinforcing member designed to receive clips from the frame of thevehicle. In addition or alternatively the reinforcing member may beprovided with small lugs, which enable it to stand away from theinterior walls of the sections of the vehicle. In this way, the need forfastening devices may be avoided and the area of contact between thestructural reinforcing member and the interior walls of the frame of thevehicle may be minimized. The clearance between the extremity of thereinforcing member and the interior walls of the frame of the vehicleand between the piece of second expandable material, when present, andthe interior walls of the frame of the vehicle should be wide enough toenable the liquid used in the electrocoat bath to flow between thereinforcing member and the interior walls of the sections of the vehiclein sufficient quantity to enable an effective anti-corrosion coating tobe deposited. The clearance must not however be too wide since this canresult in a lack of rigidity in the structure when the first expandablematerial is foamed to fill the clearance and bond the structuralreinforcing member to the interior walls of the frame of the vehicle. Weprefer that the clearance be no more than 1 centimeter and is morepreferably 3 to 10 millimeters. Provision of a clearance around thewhole structure enables a more uniform foam structure to be obtained.

The rigid reinforcing member may be made from any suitable material, forexample it may be made of metal or plastic and the material will bechosen according to the preferred fabrication method. This, in turn, isdriven by economics and the complexity of the cross section to bereinforced. Reinforcing members of simple cross sections may be preparedby extrusion whilst injection moulding may be required for more complexstructures. Metal members may be produced by stamping and/or forming.Where extrusion is used the members may be of metal or thermoplastics;where injection moulding is used thermoplastics are preferred.Polyamides, particularly glass filled polyamides are suitable materialsfor extrusion or injection moulding due to their high strength to weightratio. Alternatively injection moulding or die casting of metal alloysmay be employed. It is preferred that the moulding is provided withmeans enabling fluid drainage. For example, holes may be provided in themoulding to allow the drainage of water, which may condense in thestructure over time.

The preferred shape and structure of the reinforcing member will dependupon where it is to be located in the vehicle structure, the reinforcingfunction it is to perform, the article to be attached and the means ofattachment. The reinforcing effect may be to reduce point mobility suchas for example at the base of side and rear pillars, this isparticularly important with high-sided vehicles where the reinforcementcan reduce or prevent vehicle sway thus reducing metal fatigue. Otherparts of the vehicle which may be reinforced by the techniques of thepresent invention include roof structures, pillars, such as the Apillar, B pillar or C pillar. The invention is particularly concernedwith parts which may be used to reinforce the base of A pillars and Bpillars where the attachment may be used to attach doors and the like.

The first expandable adhesive material serves two main functions, itwill expand to fill the space between the reinforcing member and theinterior of the vehicle structure and it will also bond to the interiorwall of the structure. Accordingly, expandable adhesive material meansthat the material can be activated to both expand (typically foam) andto act as an adhesive. Activation therefore enables the first expandablematerial to expand and fill a gap between the reinforcing member and thehollow structure it is designed to reinforce and to bond to the internalsurface of the hollow structure. Accordingly, the first expandableadhesive must expand at the desired temperature and be sufficientlyadhesive to firmly bond the reinforcing member inside the vehiclestructure. Once foamed it should be sufficiently strong that it does notcontribute any weakness to the overall reinforcing effect provided.

Prior to activation, the first expandable adhesive material ispreferably dry and not tacky to the touch, since this facilitatesshipping and handling and prevents contamination.

Examples of preferred foamable materials include foamable epoxy-baseresins and examples of such materials are the products L5206, L5207,L5208 and L5209, which are commercially available from L & L Products ofRome Mich. USA, and the Betacore Products BC 5204, 5206, 5205 and 5208available from Core Products, Strasbourg, France. The product should beselected according to the rate of expansion and foam densities required.It is further preferred that the material expand at the temperaturesexperienced in the electrocoat baking oven, typically 130° C. to 150° C.

The first expandable adhesive material should be applied to at least aportion of the surface of the rigid reinforcing member that will beadjacent to an interior surface of the section of the vehicle frame thatis to be reinforced. It is preferred that the foamable material beapplied over at least part of all the surfaces of the reinforcing memberthat are adjacent to the interior surface of the vehicle section. Thefirst expandable material may be applied to the rigid reinforcing memberby bonding a strip of the material to the member, by extrusion coatingor by injection moulding. Where the reinforcing member is made byinjection moulding the expandable material may be applied by two shotinjection moulding. The material should however be applied underconditions such that no foaming takes place.

The second expandable material, when used, serves a different functionfrom the first expandable material in that it fills the entire crosssection of the hollow profile member and provides sound insulation.Typical materials from which the second expandable material can bederived include ethylene unsaturated ester copolymers such as ethylenevinyl acetate copolymers and copolymers of ethylene and acrylic monomerssuch as acrylic acid, methyl acrylate, ethyl acrylate and butylacrylate. Such polymers contain blowing agents to render them expandableand choice of the blowing agent and blowing agent initiator (sometimesknown as a kicker) can determine the temperature at which expansionoccurs. Accordingly although it is not essential that the secondexpandable material expand at the same temperature as the firstexpandable material the temperatures are preferably similar andpreferably both within the range of temperatures experienced in theelectrocoat oven, typically 130° C. to 150° C.

It is preferred that the reinforcing member coated with the firstexpandable material and optionally attached to the second expandablematerial is located within the hollow member that it is designed toreinforce in a manner that provides a clearance between the externalsurface of the coated member and the internal surface of the hollowmember. This allows for the passage of the electrocoat fluid between themember and the internal surface and also enables a uniform expansion ofthe foam around the member to provide more uniform reinforcement.Accordingly, in a preferred process for providing reinforcement andsound deadening within hollow structures such as a vehicle frame, moldedreinforcing members with the layer of first expandable material thereonand with the piece of second expandable material attached thereto areinstalled during assembly of the vehicle frame. A nut may then be placedin the means provided within the core for receipt of a nut. Locatinglugs are preferably moulded on the reinforcing member or the expandablematerial so that the reinforcing member sits within the vehiclestructure leaving a space between the member and the interior walls ofthe cavity to be reinforced, in this way the need for fastening orbonding means to attach the member to the interior walls can be avoided.

The assembled structure is then subjected to the electrocoat process inwhich it is passed through a bath of coating material and a corrosionresistant coating is deposited onto the structure by electrolysis. Thevehicle structure is then dried in an oven to provide the final coatingand the first and second expandable materials are preferably chosen sothat they are activated and foam due to the drying conditions used inthe oven employed to bake the coating on the electrocoat process. Inthis way the expandable materials will expand under the dryingconditions to provide a first foam that fills the space between therigid reinforcing member and the interior walls. The foam produces astrong bond between the reinforcing member and the interior wall. Asecond foam will be formed at the extremity of the reinforcing memberthat fills the entire cavity to provide a sound insulating baffle.Typically the coated structure is dried at around 165° C. for about 20minutes and accordingly both the foamable materials preferably expandunder these conditions. The industry is however looking to use lowerdrying temperatures and shorter drying times and this may influence thechoice of expandable adhesive materials. Once the foaming has takenplace and the foam is cured a body panel such as a door may be securedto the vehicle structure by means of a bolt mating with the nut alreadyprovided in the structural reinforcing member.

The techniques of the present invention may be used for the attachmentof parts, reinforcement and optionally the provision of sound insulationin any construction that is based on a hollow frame structure. They mayfor instance be used in the construction industry, in boats, inaircraft, and in railroad applications. The techniques are howeverparticularly useful to provide reinforcement in automobiles includingcars, trucks, caravans and the like. The techniques are particularlyuseful in the current trend towards using lighter and sometimes weakermaterials in the production of automobile sub frames where there is agreater need for reinforcement to compensate for the reduction instrength of the basic material and yet satisfy the safety requirements.This is particularly the case with the use of aluminum for theproduction of automobiles.

The invention is applicable to any instances where structuralreinforcement is to be provided at positions whose parts are to beattached. For example in vehicles it is applicable for door attachmentsincluding hatchbacks, bonnet, boot and engine attachments. Similarly theinvention is applicable to attachments in aircraft, railroad, ship andboat applications.

The present invention is illustrated by the accompanying drawings inwhich FIG. 1 shows a multisection profiled member (1) whose exteriorprofile matches the profile of the base of an A pillar of a vehicle. Themember (1) comprises an outer surface (2) and vertical and horizontalribs (3) and (4) are provided to impart improved structuralreinforcement. The member (1) is also provided with cavity means (5) forthe receipt of a nut to enable the door to be attached to the pillar,the cavity (5) is such that a nut for receipt of the bolt used to attachthe door can be slid into the cavity. The cavity is provided with armswhich hold the nut in pace. The cavity is also provided with a square orrectangular slot into which the base of the nut can be fitted in amanner that prevents rotation of the nut. Clips (6) are provided forattaching the profiled member (1) to the inner surface of the A pillar.Spacers (7) are also provided to hold the member (1) away from thepillar until foaming has taken place.

The member (1) is also provided with a first expandable adhesivematerial at various positions (8) on its surface.

A piece of second expandable material (9) is provided across the entireupper surface of the profiled member (1) which can be expanded toproduce an acoustic baffle.

FIG. 2 is an expanded view of the area of the profiled member (1) whichcontains the cavity means (5) shown in FIG. 1 providing the means forattachment. FIG. 2 shows how the nut (10) may be located within thecavity and also may be held rigidly in place by the surrounding ribs(11) which are part of the rigid member (1). FIG. 2 also shows thesquare end of the nut (4) which fits the square slot (13) formed in theprofiled member (1) in a manner that prevents subsequent rotation of thenut. A door panel may be attached to the pillar that is reinforced withthe profiled member (1) by means of a bolt that may be screwed into thenut (10). Accordingly it may be seen that this invention provides greatstrength and rigidity to the nut (10). The invention therefore allowscomparable strength with lighter weight materials.

1-14. (canceled)
 15. A method of providing structural reinforcement of sound deadening to a hollow area of a structure of a vehicle, comprising: providing a member shaped to conform to the hollow area of the vehicle wherein the member has an opening extending therethrough; disposing an expandable material upon the member while still allowing access to the opening; inserting the member within the hollow area of the vehicle with the expandable material disposed thereon; extending a fastener through the opening of the member; and fastening the fastener to a structure of the vehicle.
 16. A method as in claim 15 wherein the step of inserting occurs at a position where a door is attached to a pillar.
 17. A method as in claim 15 wherein the member includes attachment for attaching the member to the vehicle upon insertion of the member within the hollow area.
 18. A method as in claim 15 wherein, upon insertion, there is space between the member and the walls and the space provides a clearance of less than 1 cm.
 19. A method as in claim 15 wherein the hollow area is located adjacent to a location where a door of the vehicle attaches to the vehicle.
 20. A method as in claim 15 wherein the expandable material is configured to expand in an e-coat or paint oven.
 21. A method as in claim 15 wherein the member is formed of one of thermoplastic and metal.
 22. A method as in claim 15 wherein the expandable material is configured to expand at a temperature between 130° C. and about 150° C.
 23. A method as in claim further comprising passing electrocoat fluid through space between the member and walls of the vehicle defining the hollow area.
 24. A method as in claim 15 further comprising exposing the expandable material to an elevated temperature such that the expandable material expands and substantially entirely fills a cross-section of the hollow area.
 25. A method as in claim 15 wherein the structure is a pillar of the vehicle.
 26. A method as in claim 15 wherein the fastener is a bolt.
 27. A method of proving structural reinforcement or sound deadening to a hollow area of a structure of a vehicle, comprising: providing a member shaped to conform to the hollow area of the vehicle wherein the member has an opening extending therethrough; disposing an expandable material upon the member while still allowing access to the opening; inserting the member within the hollow area of the vehicle with the expandable material disposed thereon; extending a bolt through the opening of the member, the opening configured for receipt of such bolt; fastening the bolt to a structure of the vehicle wherein the structure of the vehicle is an A-pillar of the vehicle; passing electrocoat fluid through space between the member and walls of the vehicle defining the hollow area; and exposing the expandable material to an elevated temperature such that the expandable material expands and substantially entirely fills a cross-section of the hollow area.
 28. A method as in claim 27 wherein the step of inserting occurs at a position where a door is attached to a pillar.
 29. A method as in claim 28 wherein the member includes attachment for attaching the member to the vehicle upon insertion of the member within the hollow area.
 30. A method as in claim 29 wherein the space between the member and the walls is a clearance of less than 1 cm.
 31. A method as in claim 27 wherein the hollow area is located adjacent to a location where a door of the vehicle attaches to the vehicle.
 32. A system as in claim 27 wherein the expandable material is configured to expand in an e-coat or paint oven.
 33. A system as in claim 27 wherein the member is formed of one of thermoplastic and metal.
 34. A system as in claim 27 wherein the expandable material is configured to expand at a temperature between 130° C. and about 150° C. 